The present invention relates to a radio sub-system for emitting/receiving software defined radio with opportunistic secondary use, being part of a piece of radio equipment.
Generally, the invention is located in the field of radio communications. The recent emergence of software defined radio, known under the acronym of SDR for “Software Defined Radio”, sees an increasing number of applications in the field of radio communications.
A software defined radio equipment notably includes a radio emission/reception sub-system ensuring emission and/or reception of an electromagnetic signal, commonly called a “SDR Transceiver” according to the terminology. The radio sub-system is capable of operating in the sense of emission on the radio media, of reception from the radio media, or most often of both, either alternately (half duplex) or simultaneously (full duplex).
According to the state of the art, such a radio sub-system is characterized by that it necessarily has a software interface for exchange of messages or control requests and data with the software defined radio application which uses it.
The useful signal exchange between the radio emission/reception sub-system and the software defined radio application is a digital signal, typically digitized in a complex representation in base band.
The radio emission/reception sub-system includes a stage for analog processing operations, interfaced with the radio propagation medium, and a stage a digital processing operations, interfaced with the software defined radio application, separated by a digital/analog and/or analog/digital conversion.
The signal processing chain carrying out the transformation between the signal at the input and the signal at the output can only operate at the given instant for the needs of one and only one software defined radio application. Such a signal processing chain typically includes analog and/or digital filtering operations, of digital decimations and/or interpolations, of frequency transpositions, of Hilbert filtering operations, etc., is distributed between the stage for digital processing operations and the stage for analog processing operations depending on choices specific to each implementation architecture.
In addition to the digital portion of the processing chain, strictly speaking, the digital portion of the software defined radio emission/reception radio sub-system comprises the software means required for the interaction with the software defined radio application using the radio emission/reception sub-system.
The previous discussion summarizes the characteristics of a radio emission/reception sub-system in the typical case when the radio sub-system is only used by a single software defined radio application.